Uh oh. Cracking along the seat tube under the clamp...
 

All,

So, I noticed a small crack on the seat tube of my 2006 Dahon Mariner. The bike is more than 5 years old and therefore out of warranty.

Just after taking these photos, I've marked the length of the crack with a Sharpie, so that I can determine if the crack is growing. I have never ever ridden with the seatpost extended past its limit markings (in fact, I normally keep the seat post about half an inch lower than its limit), never hopped a curb, and I ride on a sprung Brooks Flyer (which I thought would absorb any excess stress.)

The following photos are taken with and without flash.

http://www.bikeforums.net/attachment...1&d=1322003454

http://www.bikeforums.net/attachment...2&d=1322003487

Any thoughts on a course of action? Repairs possible?



Thanks,
Warr

if you're the original owner, i know that there is a lifetime warranty on dahon frames. as long as you register it..or you could check with thor.

Oh, oh.:eek:
Apparently, you have not abused the bike. In fact, you seemed to follow pretty much Dahon's guidelines and suggestions on the proper use of their bikes (I should know, I once owned 2 of them). As for the course of action, the next step is yours to take. It all depends on how much money, time, and probable hassle you wish to spend on the bike. I hope you did take the time to register the bike on their Website after purchase if you bought it new. As discussed above, you could contact Dahon itself or your dealer that you bought if from if it was a new purchase for further guidance and instructions. If not possible, you might consider these choices:

• Repair it yourself (get quotes from reputable bike shops that are experienced with repairing cracked frame).
  
• Strip the bike of it's good parts and either sell those parts online as used-or keep the parts for future bikes to offset the financial loss as much as possible (my own choice of action for a previous bike).
  
• Buy another bike (the preferred option forced on most people for the flood of unrepairable or costly to repair bikes that cost more to repair than they are worth or even purchased new-like many to most imported-from-the-far-east products offered new nowadays, not just bikes).

Don't feel too bad. It is a real gamble for the longevity of most any selfsame products of any type by the comsumer.

I don't see how Thor could help here. I live only 15 miles away from Dahon's North America Headquarters. It is just a little office/warehouse combo with a few employees when I drove by on the way to visit my brother a few years back. Nothing impressive at all. I worked at the Sears Southern California Regional HQ and it was far bigger than that.

See for yourselves: http://maps.google.com/maps?q=833+Meridian+Street,+Duarte,+CA&hl=en&sll=37.0625,-95.677068&sspn=27.089481,44.736328&vpsrc=0&hnear=833+Meridian+St,+Duarte,+California+91010&t=h&z=16

Well, if this is the same 2006 Mariner you just bought on C/L for a song, then the frame is at least 4130 chromoly and weldable .... from the pictures (might be the angle) there seems to be quite a bit of 'pinching' at the top of the slot .. does it have a plastic or aluminum seat post sleeve? I'd pull the seatpost and sleeve out and see if the crack is all the way through to the inside ... you might be able fill and grind the crack early..

It might even be possible to use an aluminium seat post shim (assuming the one you have is plastic) and continue riding like that. Steveroot who used to be the kingpin on the Dahon forums has ridden with worse cracks no problem. AFAIK he rode one case where the crack was all the way through and around (so completely broken off) but he reinforced it with some sort of clamping arrangement and rode just fine.

lets see

thor

Um, I assume you meant to type more, Thor? ;-)

To answer other questions, I am not the original purchaser, it is made of 4130 ChroMo, and I do have the plastic sleeve around the seatpost. And it must be the angle of the photo - there's no pinching happening around the seat post clamp.

-Warr

As you saw the big slot has a round hole in the end,
you can drill a small hole at the end of that crack to stop it growing,

Until you can get the spot TIG re-welded, small bead, and a paint touch up..
I concur, if the shim is too small replacing it with one made to a tighter tolerance

will cause less flexing work the metal , a cause of that crack developing.

Warr email me the frame number and I will see what I can do
also make a pic from the headset for me... there were two different sizes.
Dahon has a frame and we need to find out if that is the correct one ....

In any case I have a alloy shim which I personally like better than the plastic one... it might be all what it needs, but lets explore all possibilities first ...



thor

Thanks Thor!

Message sent to what this forum thinks is your email addy. Lemme know if it's a no-show.

Have a great weekend.

-Warr

Any other thoughts, anyone?

Thor, what's the price on an aluminum shim?

-Warr

email me the addy ... we figure something out.... also still waiting for the pic we need for dahon to find out what frame it is ....
Thor

Thor,

I sent an email to you about how to take the photo, exactly (I guess I didn't quite understand what you meant), but perhaps you didn't get it?

Can you PM me your email addy? Otherwise, shoot me your email address to me at:
http://www.warrenernst.com/contact-me/the_address.jpg
and we can take this offline.

Thanks for your help.

-Warr (Warren Ernst)

(PS: email address posted as a pick in a feeble attempt to thwart spam.)